PIN prompting typically refers to merchants steering customers at the point of sale to use their debit cards and PINs instead of signature debit cards or credit cards.

Mercator estimates that merchants who adopt PIN prompting can save about $8.5 million annually per 100 million transactions.

Mercator estimates the interchange fee for a PIN-debit transaction is about 20 cents less than a signature debit transaction. Paterson says the largest “big-box” retail chains, such as Wal-Mart and Best Buy, as well as relatively high-ticket merchant chains are increasingly prompting customers to use their PINs instead of signing for transactions.

PIN prompting has not penetrated smaller merchants and is unlikely to become commonplace at such segments as fast-food restaurants that depend on quick checkouts, he says.